Editing Imported parts

My first question is this: Can I import a part say (step) and modify/edit that part?? And is there a "best" file type to import as if this is possible?

Let me better explain what I'm TRYING to do here. I'm in the jewely industry and I want to import a part I made in my design software (3design) and "flatten" it. It's a part of the ring and I want to flatten it and export as a dxf so i can then bring into corel draw and extract the lines and save as a .Plt

So I guess the real question, is can i import a model, FLATTEN IT and export back out???

Thank you for the speedy replies guys!! Troy the object I am trying to flatten is all the same thickness so I guess that is some good news. My model is "water tight" but when imported in as a step it is broken into faces.

Thanks Scott I'll be sure to take a look at your thread and see if that is what i'm after.

I guess the easierst way to explain what I'm trying to do is to import a pipe shape with cut outs and then flatten it. The pipe is all be the same thickness. I would post the step but I've not figure out how to do that on this forum yet, :/. I've attached a pic below

ok thx guys the .step is there so if you think it's possible to do flatten on this object please let me know, thanks a TON!

Edit: Ok, no need to go any further down the rabbit hole friends. i just got off the phone with tech support and was told that my step files are not exporting properly or something because once they get inside solidworks they are no longer perfectly round on the inside or out :/